public class Example4_20 {
   public static void main(String args[]) {
      char a[] = {'a','b','c','D','E','F'};
      for(int i = 0;i<a.length;i++) {
         if(Character.isLowerCase(a[i]))
            a[i] = Character.toUpperCase(a[i]);
         else if(Character.isUpperCase(a[i]))
            a[i] = Character.toLowerCase(a[i]);
      }
      for(int i=0;i<a.length;i++)
         System.out.print(""+a[i]);
   }
}
